Kneading pump



Feb. 11, 1941.

F. BURGHAUSER ETAL KNEADING PUMP Filed Feb. 1, 1939 2 Sheets-Sheet 2 N! Wb T a: W; BM 2 m H INVENTORS i amgkag k TH EIR ATTORNEYS Patented Feb. 11, 1941 KNEADING PUMP Franz Burghauser, Nuremberg, and Karl Erb, Frankfort-on-the-Main, Germany, assignors of one-half ,to Maschinenfabrik Paul Leistritz, Nuremberg, Germany, and one-half to- I. G. Farbenindustrie Aktiengeselischaft, Frankforton-the-Main, Germany Application February 1, 1939, Serial No. 253,968

In Germany February 4, 1938 1 Claim.

The present invention relates to' a kneading pump.

U. S. Patent No, 2,115,006 to Franz 'Burghauser describes a kneading pump consisting of a casing 5 and at least a right handed and a left handed worm arranged in the casing and having closely intermeshing threads, the threads of the worms being so formed that the width of the space between adjacent'fianks of each thread progressively varies from one end to the other, the main worm to which the material to be kneaded is supplied by an inlet in the casing, having a thread which provides a passage which gradually decreases in volume from the inlet to the outlet side,'the secondary worm which closely intermeshes with the main worm having a thread which provides a passage increasing in volume correspondingly towards the outlet of the casing."

Kneading pumps of all kinds of construction,

20 when charged with a materialwhich is very elastic and difilcult to treat or with a viscous liquid at a high number of revolutions, are, however, not completely filled, and, in consequence thereof, the kneading action cannot be utilized to such an extentas the construction of the machine theoretically allows. A lumpy material, too, does not entirely fill the free space around the main worm at the inlet side, the more so as the broad thread of the secondary worm impedes'the drawing in of 30 the material. In'consequence thereof only the main worm with its small thread cuts off pieces of the material and the chambers formed by this worm on conveying the material are for a certain length of the worm filled partly with air and 35 partly with the material. Only when the chambers have decreased to such an extent that they are entirely filled with the material the kneading and pressing action sets in. Thus the power of the machine is not fully utilized, since. only at 4.0 the last threads the material is pressed through the crevice. In case the lumps of the material are very large it may even happen that they are only lifted without pieces being cut off. These drawbacks do not occur-with a material which 45. enters the machine more or less by itself; a lumpy material, however, may risk the industrial utility of the kneading pump. By a mere constructive improvement of the device claimed in U. S. Patent No. 2,115,006 it 50 was not possible to remove the drawback of insuflicient drawing in of the material and a fundamentally new way had to be sought for. I Now, the present'invention is based on the observation that a filling pump or a similar device 5 may be applied for entirely filling all of the chamthat between the main worm near the inlet and 5 the casing. Thus the main worm does not close tightly with the casing at the, inlet but grasps a large volume of the material. Unneoessar ily high intermediate pressures are avoided thereby. The

worms of the filling pump rotate in such a man- 10 er that they roll in or suck in the material,

The inventive idea may be realized in various ways. For instance the main worm may be prolonged and this prolonged part mounted beneath the inlet tube may have one or several small threads whereas the corresponding prolonged part of the secondary worm or parts of the secondary worms may have one or several threads of constant or increasing breadth. On the secondary worm, preferably at the end of the inlet tube, a disk is provided which serves as a closing means for the filling pump formed by the said prolonged parts of the main and secondary worms. Instead of a disk mounted on the axle of the secondary worm a plate may be inserted in the casing through which plate the said worm is conducted.

Furthermore the said prolonged threaded parts of the worms fed by the inlet tube may supplementarily be provided with deep grooves. It is also possible to construct the corresponding part of the secondary worm without a thread and to provide a stripping edge in the casing along which the said part of the secondary worm slides.

Moreover, this part of the secondary worm may be surrounded by an endless conveying belt which serves to increase the surface of the worm drawing in the material.

Finally it is possible to arrange besides the prolonged part of the main worm at the inlet tube a third worm which closely intermeshes with the said part of the niain worm and presses the material into the latter. This feed worm intermeshing with the main worm has preferably a diameter which is a whole-numbered multiple of the diameter of the main worm, for instance about twiceor thrice'as great as the latter. In comparison ,with the main worm its action is double or triple threaded and therefore the number of 5 revolutions, when the machine is in operation, amounts to a half or a third of the revolutions of the main worm. The accompanying drawings diagrammatically illustrate some modes of kneading pumps accord- 5 ing to the invention, but they are not intended to limit it thereto:

Fig. 1 is a horizontal longitudinal section of a kneading pump,

Fig. 2 is a cross-section of this pump through the inlet tube,

Figs. 3 and 4 illustrate differently shaped Worms for the same pump,

Figs. 5 to 9 are modifications of the pump ac- 10 cording to' the invention.

In Figs. 1 and 2 the main worm a, and the secondary worm b are arranged side by side in the casing c so that the latter closely surrounds the worms from the border is of the inlet tube onward. From A 'at the inlet tube the material to be kneaded is supplied to the main worm and the secondary worm and the direction of rotation of the worms is so-as indicated by the curved arrowsthat the worms grasp the material introduced from above and, like a rolling mill, press it into the spaces between adjacent flanks of the thread. The outlet tube at B removes the material from the other end of the secondary worm. This arrangement is in principle the same for all pumps according to this invention.

Fig. 1, besides, shows a special form of the inlet ends of the worms. The space between adjacentflanks of .the thread of the prolonged part of the main worm is uniformly broad in the range of the inlet tube until it reaches the edge amm where it decreases progressively. The corresponding dimensions of the thread of the prolonged part of the secondary worm are constant but smaller, so that the main quantity of the material is conveyed to the main worm. From the edge It the spaces between the thread of the secondary worm increase so that at the end of the secondary worm the entire mass has' passed from the main worm to the secondary 40 worm by way of the space between the flanks. Near the inlet tube the casing is somewhat widened around the filling pump formed by the prolonged parts of the worms as appears from Fig. 1. p I In Fig. 3 the prolonged part of the secondary worm b is, in the range of the inlet tube, provided with a thread of increasing breadth. Thereby the material on the secondary worm is pressed into the main worm a before the worms enter the surrounding casing. In order to eifect a complete closure between the free spaces of the secondary worm and the spaces of its prolonged part beneath the inlet tube at the. edge k of the casing a disk g' (cross-section) of an outer diameter equal to the diameter of the thread of the secondary wormis provided he- 'tweenthe thread of the'secondary worm itself and the thread of its prolonged part, whereas at the corresponding part of the thread of the 0 main worm a free space I is provided.

In Fig. 4 the'broad thread at the prolonged part of the secondary worm and the space between the thread. of the prolonged part of the main worm have a somewhat smaller diameter in order to increase the capacity of the filling worms.

Whenasparingly adhering mass is to be conveyed th'e cylindric surface of the worms'may be provided at theinlet with longitudinal or bevelled flutes or they may be toothed.

For kneading some kinds of material it may be suitable to construct the prolonged part of the secondary worm in the pump without threads at the inlet. Such a pump is illustrated in Figs.

5 and 6. In the range of the inlet tube the secondary worm b has no threads but either a smooth cylindric surface having the diameter of the core of the worm or, if desired, a fluted surface as, for instance, shown in Fig. 5. The 5 material which by the inlet tube is supplied to this surface is grasped by both worms, drawn downward in the direction of the arched arrows and there at the inner edge m of the casing c it is scraped off by the secondary worm and pressed 10 into the space between the thread of the main worm. It is guaranteed thereby that also in the case of a very viscous material the free space of the main worm is completely filled.

The said grasping cylindric surface of the pro- 15 longed part of the secondary worm situated at p the inlet tube may be surrounded by an endless belt n as shown in Fig. 7. This belt which rotates together with the worm serves to increase the surface of the worm drawing in the material. 20 If desired, its outer surface may be roughened or provided with transversal bars and, besides,

it may form a conveying belt which carries the mass to be treated from outside into the pump.

A further modification of the kneading pump is illustrated in Figs. 8 and 9 where, in order to shorten the kneading worms, a further short feed worm E is mounted in the range of the inlet tube beside the main worm and preferably parallel to it. Machines of this type may be much 3 shorter than usual for fulfilling the purpose of the invention and at high pressures they are therefore considerably less stressed. As shown in Fig. 9, the action is increased by the fact that the diameter of the feed worm E is about twice as great as that of the kneading worm and that, therefore, in case the threads intermesh, the revolutions are reduced to half the number and the action of the worm is double threaded.

We-claim:

A kneading pump consisting of a casing and at least a right handed and a left handed worm arranged in the casing and having closely intermeshing threads, the threads of the worms being so formed that the width of the space between adjacent fianks of each thread progressively varies from one end to the other, the main worm to which the material to be kneaded is supplied by an inlet in the casing, having a thread which provides a passage which gradually decreases in volume from the inlet to the outlet side, the secondary worm which closely intermeshesv with the main worm having a thread which provides a passage increasing in volume correspondingly towards the outlet of the casing, a worm having at least one small thread being organically connected with the main worm and a worm having a thread which gradually increases in the direction of movement of the material being organically connected .with at least one secondary worm, these auxiliary worms which form a worm pump and act as filling pump, forming a free space with the casing which exceeds that between the main 65 worm near. the inlet andthe casing, the worms of the-said filling pump rotating in such a manner that they roll the material into the pump,

the worm connected with the secondary worm being provided with a disk atthe end of the 70 inlet tube which disk serves as closing means toward the corresponding secondary worm.

- FRANZ BURGHAUSER.

KARL ERB. 

